Persistence Assessment Tool

Persistence Assessment Tool (PAT)

The Persistence Assessment Tool (PAT) has been developed by Ricardo, in collaboration with Concawe and Cosmetics Europe and with in-kind support from Cefic-LRI and ECETOC, in response to the growing regulatory focus on the environmental persistence of chemicals. The PAT supports regulators and industry in conducting complex persistence assessments.

Background

Regulatory persistence assessments require the comparison of degradation half-lives with defined criteria in relevant environmental compartments, while considering all relevant lines of evidence (LoE) together in a weight-of-evidence (WoE) approach. However, current guidance provides limited support for evaluating data quality and integrating diverse data into a transparent and consistent WoE determination. The Persistence Assessment Tool (PAT) addresses this gap by providing a structured, transparent and science-based framework, with the goal of improving the consistency, transparency and robustness of chemical assessments required under global regulations.

What the PAT does

The tool offers a clear and structured methodology to:

• Systematically gather and store information on persistence
• Evaluate data quality
• Carry out a robust and transparent weight of evidence determination
• Asses persistence in line with global regulatory frameworks

Alignment with guidance

As described in Hughes et al., 2025, the PAT methodology has been developed in accordance with the principles of the EU REACH regulatory framework, relevant test guidelines and guidance, while remaining customisable to accommodate different regulatory practices. PAT is also identified as a weight-of-evidence tool for persistence assessments in the new ECHA Guidance on the Application of the CLP Criteria.